Power jet timing mechanism



' March 20, 1934. E, DODSON 1,951,927

POWER JET TIMING MECHANISM Filed March 24, 1933 4 Sheets-Sheet l March 20, 1934. E. DODSON 1,951,927

POWER JET TIMING MECHANISM Filed March 24, 1933 4 Sheets-Sheet 2 March 20, 1934. E. DoDsbN ,9

POWER JET TIMING MECHANISM Filed March 24, 1933 4 Sheets-Sheet 3 March 20; 1934. E. DODSON 1,951,927

' POWER JET TIMING MECHANISM Filed March 24, 1933 4 Sheets-Sheet 4 Patented Mar. 20, 1934 UNITED STATES PATENT OFFICE Application March 24, 1933, Serial No. 662,589

In Great Britain June 2, 1932 14 Claims. (Cl. 123-75) This invention relates to means for controlling supercharged and high compression ratio aircraft engines (hereinafter termed supercharged aircraft engines) which in the ordinary way are controlled by the pilot by means of a throttle lever. In such engines a known device called a boost control automatically prevents the pilot from opening the carburetter throttle more than is safe for a given altitude, while a power jet 19 is provided to enable a richer mixture to be obtained at full throttle for maximum power, and a weaker mixture for cruising, when the throttle is partly closed and the power jet is out of action. The power jet, which is a known feature in modern carburetters is used in ordinary engines at full throttle only, the purpose being to obtain a richer mixture at full throttle for maximum power,'and a weaker mixture for cruising, when the throttle is partlyclosed and the power jet is 20 out of action.

The object of this invention is to permit maximum power to be secured at all altitudes while permitting of economical cruising at every altitude at which the engine is to be used.

The invention consists of operating the power jet by interconnection with the throttle or its positions giving less than full permitted power at any height.

The interconnection between the carburetter throttle lever, the pilots throttle control and the power jet changes the ratio of movement between the throttle lever and the power jet opcrating lever so as to cause the operation of 40 the power jet to occur at a progressively more open throttle position as the atmosphere becomes less dense, until when a certain altitude or reduction of density is reached, the power jet'is in operationonly at full throttle.

A further object of the present invention is to overcome the difliculties'which occur when the controls are independent of each other and are spread over difierent parts of the engine and to facilitate lubrication, protection from dust, in-

stallation and adjustment and, in the case wherethe throttle valve in accordance with induction pipe pressures, an altitude control device and an operating device for the power jet in the carburetter are constructed as a unit mounted in a control box, and these controls are combined by interconnection within the box to effect the actuation and adjustment of the operating device of the power jet by the throttle control device and the altitude control device.

The invention will now be described, by way of example, with reference to two forms of construction in which the control'ior timing the power jet is combined with other controls in a control box. In the accompanying drawings:--

Fig. 1 illustrates diagrammatically the various means for effecting operation of the controls and means to be controlled by said controls with their interconnections with the control box.

Fig. 2 is a sectional elevation of the control box drawn to an enlarged scale and illustrating part of the control mechanism contained. therein.

Fig. 3 is a similar view to Fig. 2 but showing the remainder of the control mechanism contained in the control box.

Fig. 4-is a similar view to Fig. 1' but illustrating a modification of the means for efiecting operation of the control.

Fig. 5 is a fragmentary view illustrating the exterior end of one of the spindles mounted in the control box and showing the indicating dial andexternal arm.

Thecontrol box comprises two fiat sides a, a spaced apart, through which pass the spindles to which the control means are connected. One of these spindles b (herein termed a throttle control spindle) is connected at one of its ends where it extends through one side of the casing by means of a fixed arm b and through the intermediary of any suitable connecting device such as the link I) to the pilots control b for the throttle valve. On this throttle control spindle b interiorly of the casing is fixed an'arm b which is connected by a link b to one end b of a throttle control device consistingof the lever 12'' pivotally mounted on a central pivot b and which is connected at its opposite end 22 by means of a link 22 to an 'arm I) which is in turn fixed to another spindle b (herein termed the throttle valve spindle) passing through the side wall in the casing and connected exteriorly by arm b and link I) to the engine throttle valve 0. By this means adjustments of the pilot's throttle control are communicated through the mechanism in the casing to the engine throttle valve 110 The central pivot b is fixed on the end of an arm (1 rigid with a boost control spindle d which carries exteriorly an arm 11 connected by link d to a known boost control unit d which is adapted. to adjust the boost control spindle in accordance with changes inthe induction pipe pressures so as to rock the throttle control lever about its point of attachment to the link 12 as a fulcrum and thereby automatically adjust the throttle valve 0 relatively to the setting of the pilots throttle control b Exteriorly on the opposite end of the throttle control spindle b to that carrying the arm b an arm b is fixed which is connected by a link I) to a carburetter pump it.

Another e of the spindles in the box (herein termed the altitude control spindle) has its one end connected exteriorly of the casing by arm 6 and link e to the pilots altitude control e while the opposite end is connected exteriorly of the casing by arm 6*, link e and arm a to a mixture strength control valve 1 in the carburetter g which is adapted to regulate the proportion by weight of air to liquid fuel and thus correct the carburetter for changes in altitude.

The power jet operating device consists of a control lever 71. (Figs. 2 and 3) located interiorly of the casing connected at one end h to the link Z3 and arm b by means of the pin it on the arm 0 engaging in slot h and is connected at its opposite end 11* by means of a link h to an arm 71. on a spindle h" (herein termed the power jet spindle) which is exteriorly connected by arm h (Fig. 4) and link 71. to a lever 12. acting on the Valve n of the power jet h, of the carburetter so that the power jet valve is operated by the mechanism controlling the throttle valve. In order to enable the timing of the power jet to be effected by the controls according to the present invention, the power jet lever it has its pivot 11. (Fig. 3) mounted on an arm h which is adjustable on a fixed pivot 72. and this arm n is provided with a bowl n running in a cam slot e in a sector e fixed on the altitude control spindle e. The can slot has a sloping portion e which alters the power jet timing effected by the power jet lever so that it progressively delays the bringing into action of said jet to a more open throttlefposition as height is gained until the rated height is reached. A concentric portion e of the cam slot is provided so that at and above the rated height the power jet is only in action at full throttle. The timing of the power jet is, therefore, effected by the altitude control spindle in addition to the correction of the carburetter previously described. The spindle e and cam sector e constitute the altitude control device.

Instead of connecting the altitude control spindle exteriorly of the casing with the pilot's altitude control this spindle may be connected as shown in Fig. 4 with a known aneroid control device 1' which is actuated by difference in atmospheric pressure and which effects the necessary adjustment of said spindle.

The arms 5 Z2 I1 (1 e e and h are formed on one side with serrations (notshown) which correspond with and engage with serrations 7' on the ends of the spindles b, I)", 41 e and it against which they are held by nuts 7' so that by slackening the nuts said arms can be adjusted relatively to the spindles and thereby fixed in any adjusted position. Dials 9' are fixed to the ends of each of the spindles so that the arms can be fixed in the required position relative to the internal mechanism, so as to enable this properly to actuate or be actuated by the external mechanism to which said arms are connected.

Alternatively, instead of altering the power jet timing by means of an altitude control for correcting the carburetter, as previously described, this may be altered by means for adjusting automatically the position of ignition in the cycle of an aircraft engine in accordance with changes in altitude as described, or by any other equivalent pressure sensitive means.

In cases where aneroids are provided as part of the controlling means these may also be located inside the control box. This will facilitate the supply of fluid pressure or other source of power for actuating relays associated with the aneroids since the fluid pressure or other power can be merely carried up to the control box by single conduits and distributed to the various relays interiorly thereof.

It will thus be observed that by means of this invention the timing of the power jet is such that this can be brought into action at all maximum permissive positions of adjustment of the throttle in accordance with the altitude at which the machine is being flown. Thus at sea level, the carburetter throttle is restrained to a partly open position by the boost control apparatus, but the power jet can be brought into action at the position of maximum opening and by a slight closing movement of the carburetter throttle, the power jet is cut off and the engine runs on an economical cruising mixture. When, however, the machine is at the rated height, say, 10,000 feet, introduction of the power jet on the full forward movement of the carburetter throttle lever takes place when the,throttle is fully opened, and a slight return of the throttle lever while the throttle has a considerable opening, cuts out the power jet and permits the engine to run on a more economical mixture.

What I claim as my invention and desire to secure by Letters Patent is:

1. In supercharged aircraft engines, the combination of, a carburetter having a manually operated throttle and having a power jet, means for restricting the opening of the throttle in accordance with induction pipe pressures, means for bringing said power jet into action at a predetermined position of the throttle and means for altering the position of the throttle at which the power jet is brought into action in accordance with changes in altitude, whereby the power jet is in operation at maximum permitted throttle opening at any height.

2. In supercharged aircraft engines, the combination of, a carburetter having a manually operated throttle and having a power jet, means for restricting the opening of said throttle under the control of induction pipe pressures, means for interconnecting said power jet with the throttle adapted to bring the power jet into action at a pre-determined position of the throttle, an altitude control device, and means for controlling the interconnection of.the power jet with the throttle by said altitude control device in order that the power jet is brought into action at maximum permitted throttle opening at any height.

3. In supercharged aircraft engines, the combination of, a carburetter having a manually operated throttle and having a power jet, means for restricting the opening of said throttle under the control of induction pipe pressures, means for interconnecting said power jet with the throttle so that the power jet is brought into action at a pre-determined position of the throttle, a handoperated altitude control device, a lever connected at one end to the power jet and at its other end to the throttle and pivoted intermediate its ends, means connecting said altitude control deviceto said pivot in order to adjust the position at which the power jet is brought into action by the throttle according to changes in altitude.

4. In supercharged aircraft engines, the combination of, a carburetter having a manually operated throttle and having a power jet, means for restricting the opening of said throttle under the control of induction pipe pressures, means for interconnecting said power jet with the throttle so that the power jet is brought into action at a pre-determined position of the throttle, a pressure sensitive altitude control device, a lever connected atone end to the power jet, connected at its opposite end to the throttle and pivoted intermediate its ends and means connecting said altitude control device to said pivot in order to adjust the position at which the power jet is brought into action by the throttle in accordance with changes in altitude.

- 5. Insupercharged aircraft engines, tlrecombination of, a carburetter, a carburetter throttle, a pilots throttle control lever, interconnecting means between said throttle and said throttle control lever, a boost control device connected to said interconnecting means in order to restrict the maximum permissible throttle opening in accordance with induction pipe pressures, a valve controlled power jet in said carburetter, operating means connecting the power jet valve to said interconnecting means, an altitude control device and means connecting said operating means to said altitude control device in order toadjust the position of the throttle 'at which the power jet is brought into action in accordance with changes in altitude.

6. In supercharged aircraft engines, the combination of, a carburetter, a carburetter throttle, a pilots throttle control lever, interconnecting means between said throttle and said throttle control lever, a boost control device connected to said interconnecting means in order to restrict the maximum permissible throttle opening in accordance with induction pipe pressures, a valve controlled power jet in said carburetter, a lever connected at one end to said interconnecting means, connected at its opposite end to the power 'jet valve and pivoted intermediate its ends, a

pressure sensitive altitude control device and means connecting the-pivot of said lever to said altitude control device in order to adjust the position of the throttle at which the power jet is brought'into action in accordance with changes in altitude.

7. Means for controlling supercharged aircraft engines comprising, a control box, a throttle control device in said control box for restricting open- .ing of the carburetter throttle opening in accontrol device, whereby the operation by the throttle control device is altered by the altitude control device in accordance with changes in altitude.-

it. Means for cqntrolling supercharged aircraft engines having a carburetter'with a manually-operated throttlev and a power' 'jet comprising a control box, a throttle control device said control box for restricting opening of the carburetter throttle in accordance with induction pipe-pressures, means exteriorly of said control box for connecting said throttle control device to said throttle and to a pilots throttle control, an altitude control'devic'e in said control box, a power jet operating device in said control box, means for connecting said power jet operating device to the power jet, and means interconnecting said power jet operating device with said throttle control device and with said altitude control device whereby the power jet is brought into action at a position of the throttle which changes in accordance with changes in altitude.

9. Means for controlling supercharged aircraft engines having a manually operated carburetter throttle and-a power jet comprising a control box, a throttle control device in said control box for restricting opening of the carburetter throttle in accordance with induction pipe pressures, means exteriorly of said control boxfor connecting said throttle control device to said throttle and to a pilots throttle control, an altitude control device in said control box, a power jet operating device in said control box connected for operation by the throttle control device, means exteriorly of said control box for connecting said power jet operating device to the power jet adapted to bring the power jet into action at a predetermined position of the throttle, and means interconnecting said altitude control device with said power jet operating device for adjusting the positionof the throttle at which the power jet is brought into action in accordance with changes in altitude.

10. Means for controlling supercharged aircraft engines having a manually operated carburetter throttle and a power jet comprising a control box, a throttle control device in said control box, means connecting said throttle control device to the carburetter throttle, means connecting said throttle control device to the pilots throttle control, a boost control device, means connecting said throttle control device to the boost control device for restricting opening of the carburetter throttle in accordance with induction pipe pressures, an altitude control device in said control box, means for connecting said altitude control device exteriorly of the control box to a hand operated altitude control, a power jet operating device connected for operation by the throttle control device, means for connecting said power jet operating device to the power jet adapted to bring the power jet into action at a pre-determined position of the throttle, and means interconnecting said altitude control device with said power jet operating. device for adjusting the position of the throttle at which the power jet is brought into action in accordance with changes in altitude.

11. Means for controlling supercharged aircraft engines having a manually operated carburetter throttle and a power jet comprising a control box, a throttle control device in said control box, means connecting said throttle control'device to the carburetter throttle, means connecting said throttle control device to a pilots throttle control. a boost control device, means for connecting said boost control device to said throttle control device for restricting opening of the carburetter throttle in accordance with induction pipe pressures, an altitude control device in said control box, a'pressure sensitive device connected to said altitude control device adapted automatically to adjust said altitude control device for yariation in pressure consequent upon changes in altitude, a power jet operating device connected All) for operation by the throttle control device, means exteriorly of said control box for connecting said power jet operating device to the power jet adapted to bring the power jet into action at a. pre determined position of the throttle, and means interconnecting said altitude control device with said power jet operating device for adjusting the position of the throttle at which the power jet is brought into action in accordance with changes in altitude.

12. Means for controlling supercharged aircraft engines having a carburetter witha manually operable throttle and a power jet, comprising a control box, a throttle control lever in said box pivoted at its centre, a throttle control spindle extending through said box carrying an external arm connected to a pilots throttle control and an internal arm connected to one end of the throttle control lever, a throttle valve spindle extending through said box carrying an external arm connected to the carburetter throttle and an internal arm connected to the opposite end of the throttle control lever to that to which the throttle control spindle is connected, a boost control spindle extending through said box carrying an external arm connected to a boost control device and an internal arm carrying at its end the pivot of the throttle control lever, an altitude control spindle extending through said box carrying an external arm connected to an paltie tude control device and carrying an internal sector having a cam slot, a power jet control lever in said box connected at one end to the internal arm on the throttle control spindle and pivoted intermediate its ends, a power jet spindle extending through said control box carrying an external arm connected to the power jet and an internal arm connected to the free end of the power jet control lever, an arm mounted on a fixed pivot and carrying at its end the pivot of the power jet lever, and a bowl on the power jet lever adapted to run in the cam slot of the sector, whereby the position of the throttle at which the power jet is brought into action is adjusted in accordance with changes in altitude.

13. Means for controlling supercharged aircraft engines having a carburetter with a manually operable throttle and a power jet, comprising, a control box, a throttle control lever in said box pivoted at its centre, a throttle control spindle extending through said box carrying an internal arm connected to one end of the throttle control lever, an external arm adjustably fixed on said throttle control spindle and connected to a pilots throttle control, a throttle valve spindle extending through said box carrying an internal arm connected to the opposite end of the throttle control lever to that to which the throttle control spindle is connected, an external arm adjustably fixed on said throttle valve spindle and connected to the carburetter throttle, a boost control spindle extending through said box having an internal arm carrying at its end the pivot of the throttle control lever, an external arm adjustably fixed to said boost control spindle and connected to a boost control device, an altitude control spindle extending through said box carrying an internal sector'having a cam slot, an external arm adjustably fixed on said altitude control spindle and connected to an altitude control device, a power jet control lever in said'box connected at one end to the internal arm on the throttle control spindle and pivoted intermediate its ends, a power jet spindle extending through said control box carrying an internal arm connected to the free end of the power jet control lever, an external arm adjustably fixed on said power jet spindle and connected to the power jet, an internal arm mounted on a fixed pivot and carrying at its end the pivot of the power jet lever, a bowl on the power jet lever adapted to run in the cam slot of the sector, and an indicating dial fixed exteriorly to each of said spindles, whereby said external arms may be fixed in any position to suit the mechanism to which they are connected. v

14. In a supercharged aircraft engine, the combination of, a carburetter with a manually operable throttle, a carburetter mixture strength control valve, and a valve controlled power Jet, a control box, a throttle control lever insaid box pivoted at its centre, a throttle control spindle extending through said box carrying an external arm connected to a pilots throttle control and an internal arm connected to one end of the throttle control lever, a throttle valve spindle extending through said box carrying an external arm connected to the carburetter throttle and an internal arm connected to the opposite end of the throttle control lever to that to which the throttle control spindle is connected, a boost control spindle extending through saidtbox carrying an external arm connected to a boost control device and an internal arm carrying at its end the pivot of the throttle control lever, an altitude control spindle extending through said box carrying at one end an external arm connected to an autitude control device and at its opposite end an external arm connected to the carburetter mixture strength control valve and carrying an internal sector having a cam slot, a power jet control lever in said box connected at one end to the internal arm on the throttle control spindle and pivoted intermediate its ends, a power jet spindle extending through said control box carrying an external arm connected to the power jet valve and an internal arm connected to the free end of the power jet control lever, an arm mounted'on a fixed pivot and carrying at its end the pivot of the power jet lever, and a bowl on the power jet lever adapted" to run in the cam slot of the sector, 

